Various arrangements have been used to control the pressure and/or flow in fluid systems. In many of these previous arrangements, by-pass valves have been used to by-pass fluid from the supply conduit. These types of valves normally require that the valving element move a long distance in order to provide good proportional control. Likewise, in order to get good proportional control these valves have been controlled by pilot fluid lines or by manual input. In the various attempts to control these valves electrically, complicated circuits had to be used thus making the control complex and expensive. In order to control a valve arrangement electrically, it is necessary to provide an electrical coil that has a high force over a long range of travel. If one was available, it would be both large and expensive. Hold coil assemblies have been know and used to hold a valve or lever in a desired location once it has been moved to the desired location. These types of hold coil assemblies have high hold forces but have limited longitudinal movement. It has proven to be quite difficult to set and/or adjust the gap between the coil and the holding plate. It is known that in order to obtain the maximum force from the hold coil, the gap or spacing between the hold coil and the hold plate must be accurately controlled. It is desirable to have a valve arrangement that can be electrically and proportionally controlled over a short distance while maintaining the maximum holding force.
The subject invention is directed to overcoming one or more of the problems as set forth above.